Florli

Houseplant problems

Black spots on plant leaves

Dark color by itself does not identify a cause. A wet expanding lesion needs a different response from a dry scar formed where a leaf touched cold glass.

Cold injury

Dark tissue can form after contact with glass or a cold draught.

Excess moisture

Soft darkening near the base may accompany root or stem rot.

Infection

Expanding spots with margins and similar marks on several leaves deserve caution.

More useful detail

How to narrow down the cause

What supports this cause

Rate of change, moisture and a match with a recent event are more useful than color alone.

What can look similar

Naturally dark pigment, old dry damage and surface dirt can look similar.

Problem

What to do step by step

  1. 1

    Isolate the plant if lesions are wet or expanding quickly.

  2. 2

    Remove only badly affected tissue with a clean tool and correct the growing conditions.

  3. 3

    Record the date, watering and temperature, then compare the extent after several days.

Observation

What to watch next

  • Spot margins stop moving.
  • Stems and roots remain firm.
  • No new lesions appear on fresh leaves.
Important

Do not apply a fungicide on color alone. Rule out cold, spray injury and root problems first.

Florli

Related guides and features

Library Houseplant problems Identify common houseplant symptoms, pests and watering problems. Start with observation instead of treating by guesswork. Read the guide → Problem Brown spots on leaves Brown spots may follow sun scorch, cold, watering stress or disease. Their shape, location and speed of spread help narrow down the likely cause. Read the guide → Feature Plant problem checker Florli helps you organize symptoms, consider possible causes and choose a cautious next step without presenting an uncertain result as a definite diagnosis. Read the guide →
Sources and further reading: University of Maryland Extension: diagnosing indoor plant problems Royal Horticultural Society: leaf damage on houseplants

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Prepared by Florli. Reviewed October 15, 2026. This is general guidance. Sources are listed with each guide, and every decision should reflect the species, location, weather and the plant’s current condition. How Florli creates its guides.